1. Field of Invention
The invention relates generally to optical communication networks and in particular to methods and systems for providing protection in an optical communication network.
2. Description of Related Art
Communication networks often include protection mechanisms to reroute signals in the event of a service interruption. Primary causes of service interruption are link failures and networking equipment failures. Link failures may be caused by failure of the transmission medium, such as the cut of an optical fiber cable, or by failure of an active component that affects all the optical channels on a dense wavelength division multiplexed (DWDM) link, such as an optical amplifier. With carrier-class optical networking equipment, the most likely cause of equipment failure is failure of an isolated optical channel interface.
A variety of protection techniques exist in order to provide protection against service interruption. For example, a 1+1 protection scheme provides a redundant protection path for each working path. A switch at the receiving end of the working path can switch to receive the redundant signal on the protection path if signal quality is deteriorated on the working path. Another known protection scheme is 1:1 protection in which a protection path is associated with each working path, but the protection path is not utilized until signal quality is deteriorated on the working path. Another known protection scheme is 1:N protection in which a protection path is associated with multiple working paths. If signal deterioration is detected on one of the working paths, traffic is redirected to the protection path.